Affiliated Packages: APLpy and WCSAxes

You can install the required packages by doing:

pip install aplpy wcsaxes


APLpy (the Astronomical Plotting Library in Python) is a Python module aimed at producing publication-quality plots of astronomical imaging data in FITS format. The module uses Matplotlib, a powerful and interactive plotting package. It is capable of creating output files in several graphical formats, including EPS, PDF, PS, PNG, and SVG.

APLpy pre-dates Astropy, but has been updated to match requirements to be included as an Astropy-affiliated package.

In [1]:
import aplpy
%matplotlib inline
import matplotlib.pyplot as plt

f = aplpy.FITSFigure('data/msx.fits')
f.show_colorscale(vmin=0, vmax=1.e-4, cmap='viridis')
f.show_contour('data/msx.fits', colors='black')
/sw/lib/python3.4/site-packages/matplotlib/ MatplotlibDeprecationWarning: This has been deprecated in mpl 1.5, please use the
axes property.  A removal date has not been set.
  warnings.warn(_get_axes_msg, mplDeprecation, stacklevel=1)

One downside of APLpy is that the ways of customizing figures is not always consistent with the Matplotlib API so it can be a bit confusing in some cases to switch between one and the other. So we have developed a new package called WCSAxes which aims to provide a more consistent user experience. In future, APLpy will be updated to use WCSAxes behind the scenes and will also provide more convenience layers on top of that package.


Making basic plots

To make a similar plot to the one above, you would do the following:

In [2]:
from astropy.wcs import WCS
wcs = WCS('data/msx.fits')

from import fits
data = fits.getdata('data/msx.fits')
In [3]:
fig = plt.figure(figsize=(8,8))
ax = fig.add_subplot(1, 1, 1, projection=wcs)
ax.imshow(data, vmin=0, vmax=1.e-4, origin='lower')
ax.grid(color='white', alpha=1, ls='solid')
ax.set_xlabel("Galactic Longitude")
ax.set_ylabel("Galactic Latitude")